1. Field of the Invention
This invention relates to video storage disks and the method of preparing the same.
2. Prior Art
Present day video storage disks are used to receive optically transmitted information which can be stored in thin film layers of radiation or thermal sensitive materials. The stored information can be read by optical techniques.
Typically, these disks are comprised of a substrate having disposed thereon radiation sensitive materials such as chalcogenide glasses or polymeric films having dyes embedded therein (for a comprehensive review of optical storage media see R. A. Bartolini et al, "Review and Analysis of Optical Recording Media", Optical Engineering, Vol. 15, No. 2, pages 99-108, 1976). In these disks the adsorption of actinic radiation causes a hole or crevice to be formed in the irradiated region. These deformations are optically read. Other materials employed in video disks undergo photochromism when exposed to actinic radiation. For example, azo-based dyes in a polymer matrix are coated on a substrate. When exposed to actinic radiation these dyes undergo absorption spectrum changes which can be fixed chemically to provide optically patterned information.
Although present day video storage materials have proven adequate that they have not met all the necessary property requirements necessary for video disk applications. For example, materials in order to be useful as video disk imaging media must have:
1. the ability to optically receive video information; PA0 2. the ability to store this information in high density, e.g., on the order of 1 micron images; PA0 3. provide high optical contrast between data images and background; PA0 4. be capable of absorbing suitable wavelength for detection of the stored information; PA0 5. have appropriate mechanical properties, such as being capable of strongly adhering to substrates and having uniform film forming properties; and PA0 6. they must have long term stability of the stored video information.
What has been discovered here is a class of materials which meet all of the above requirements. These materials are modified tetraheterofulvalene derivatives. The materials disclosed herein are found to provide high resolution video storage, i.e., better than 1 micron optically detectable images.